Mariadb server constanlty crashing [Error 2013] – Debian

I know this problem was asked several times, but no solution worked for me so far. I am struggling with this for over 2 weeks and I am out of options.

System:Ubuntu 18.04 LTS
MySQL version:mysql Ver 15.1 Distrib 10.4.11-MariaDB, for debian-linux-gnu (x86_64) using readline 5.2

I suspect it may be a problem with one large database (over 4GB) I had to recover from frm idb. I know the method of recovery was successful after recovery of single table I checked and the data was there, not sure if with the other tables something is not corrupted BUT:

I tried recovery method described here and problem is even when I do mysqlcheck --all-databases I get error: 2013: Lost connection to MySQL server during query when executing 'CHECK TABLE ... ' so unable to check.

From what I see in syslog server also crashed when I log into mysql and do use epffilm;
Using other advice from SO i created /etc/my.cnf :

[mysql]
connect_timeout = 43200
max_allowed_packet = 2048M
net_buffer_length = 512M
debug-info = TRUE

also content of my /etc/mysql/my.cnf:

client]
port        = 3306
socket      = /var/run/mysqld/mysqld.sock

#socket     = /run/mysqld/mysqld.sock
# Here is entries for some specific programs
# The following values assume you have at least 32M ram

# This was formally known as [safe_mysqld]. Both versions are currently parsed.
[mysqld_safe]
socket      = /var/run/mysqld/mysqld.sock
nice        = 0

[mysqld]
#
# * Basic Settings
#
user        = mysql
pid-file    = /var/run/mysqld/mysqld.pid
socket      = /var/run/mysqld/mysqld.sock
port        = 3306
basedir     = /usr
datadir     = /var/lib/mysql
tmpdir      = /tmp
lc_messages_dir = /usr/share/mysql
lc_messages = en_US
skip-external-locking
#
# Instead of skip-networking the default is now to listen only on
# localhost which is more compatible and is not less secure.
bind-address        = 127.0.0.1
#
# * Fine Tuning
#
max_connections     = 100
connect_timeout     = 1000000
wait_timeout        = 600
max_allowed_packet  = 1073741824
thread_cache_size       = 128
sort_buffer_size    = 4M
bulk_insert_buffer_size = 16M
tmp_table_size      = 32M
max_heap_table_size = 32M

net_read_timeout = 31536000
net_write_timeout = 31536000


#
# * MyISAM
#
# This replaces the startup script and checks MyISAM tables if needed
# the first time they are touched. On error, make copy and try a repair.
myisam_recover_options = BACKUP
key_buffer_size     = 128M
#open-files-limit   = 2000
table_open_cache    = 400
myisam_sort_buffer_size = 512M
concurrent_insert   = 2
read_buffer_size    = 2M
read_rnd_buffer_size    = 1M
#
# * Query Cache Configuration
#
# Cache only tiny result sets, so we can fit more in the query cache.
query_cache_limit       = 128K
query_cache_size        = 64M
# for more write intensive setups, set to DEMAND or OFF
#query_cache_type       = DEMAND
#
# * Logging and Replication
#
# Both location gets rotated by the cronjob.
# Be aware that this log type is a performance killer.
# As of 5.1 you can enable the log at runtime!
general_log_file        = /var/log/mysql/mysql.log
general_log             = 1
#
# Error logging goes to syslog due to /etc/mysql/conf.d/mysqld_safe_syslog.cnf.
#
# we do want to know about network errors and such
log_warnings        = 2
#
# Enable the slow query log to see queries with especially long duration
#slow_query_log[={0|1}]
slow_query_log_file = /var/log/mysql/mariadb-slow.log
long_query_time = 10
log_slow_rate_limit = 1000
log_slow_verbosity  = query_plan

#log-queries-not-using-indexes
#log_slow_admin_statements
#
# The following can be used as easy to replay backup logs or for replication.
# note: if you are setting up a replication slave, see README.Debian about
#       other settings you may need to change.
#server-id      = 1
#report_host        = master1
#auto_increment_increment = 2
#auto_increment_offset  = 1
log_bin         = /var/log/mysql/mariadb-bin
log_bin_index       = /var/log/mysql/mariadb-bin.index
# not fab for performance, but safer
#sync_binlog        = 1
expire_logs_days    = 7 
max_binlog_size     = 100M

# If applications support it, this stricter sql_mode prevents some
# mistakes like inserting invalid dates etc.
#sql_mode       = NO_ENGINE_SUBSTITUTION,TRADITIONAL
#
# * InnoDB
#
# InnoDB is enabled by default with a 10MB datafile in /var/lib/mysql/.
# Read the manual for more InnoDB related options. There are many!
default_storage_engine  = InnoDB
innodb_buffer_pool_size = 6G 
innodb_log_buffer_size  = 512M
innodb_file_per_table   = 1
innodb_open_files   = 400
innodb_io_capacity  = 400
innodb_flush_method = O_DIRECT
#
#
# Helpful with recovery
#
innodb_force_recovery=3
innodb_purge_threads=0
# * Security Features
#
# Read the manual, too, if you want chroot!
# chroot = /var/lib/mysql/
#
# For generating SSL certificates I recommend the OpenSSL GUI "tinyca".
#
# ssl-ca=/etc/mysql/cacert.pem
# ssl-cert=/etc/mysql/server-cert.pem
# ssl-key=/etc/mysql/server-key.pem

#

# Allow server to accept connections on all interfaces.
#
#bind-address=0.0.0.0
#
# Optional setting
#wsrep_slave_threads=1
#innodb_flush_log_at_trx_commit=0

[mysqldump]
quick
quote-names
max_allowed_packet  = 1024M

[mysql]
#no-auto-rehash # faster start of mysql but no tab completion

[isamchk]
key_buffer      = 16M

#
# * IMPORTANT: Additional settings that can override those from this file!
#   The files must end with '.cnf', otherwise they'll be ignored.
#
!include /etc/mysql/mariadb.cnf
!includedir /etc/mysql/conf.d/

Any insight is appreciated.
Update:
I put a crash log on pastenbin